Method of tobacco sucker control



United States Patent 3,326,664 METHOD OF TOBACCO SUCKER CONTROL Tien C. Tso, Beltsville, Md, assignor to the United States of America as represented by the Secretary oat Agriculture No Drawing. Filed Jan. 10, 1964, Ser. No. 337,100 Claims. (Cl. 712.6)

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grantsublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a method for controlling the growth of suckers in tobacco plants. More particularly, it relates to the use of certain fatty acid derivatives to control sucker growth in tobacco plants.

An established process for tobacco farmers is to remove the stem apex, including flowers and some top leaves, near the stage of plant maturity to stimulate the development of the remaining leaves and to obtain desirable physical and chemical properties for the best utility. This process is commonly known as topping. After such an operation, axillary buds, or suckers, start to develop, and these suckers have to be continuously removed to achieve the purpose of topping. Usually the removal of suckers is carried out by hand, which is a laborious and time-consuming process. Certain chemical growth-control agents have been suggested; but while some of these provide adequate inhibition of sucker development and are in commercial use, other metabolic changes are induced which are considered undesirable in tobacco quality. In addition, there has been some question of undesirable residues of these agents in the leaf tissue.

It is an object of this invention to provide a method and compositions which can successfully control sucker growth without any adverse effects on the tobacco leaves and on the resultant products made therefrom. Another object is to provide compositions effective to control sucker growth which will not introduce any undesirable foreign residues into the tobacco leaf tissues. Other objects and benefits will be apparent to those skilled in the art from the description of the invention which follows:

In general, in accordance with this invention, it has been found that certain fatty acid esters, when applied to the upper portions of decapitated, or topped, tobacco plants, or to plants on which the flower buds have newly formed, will accomplish the foregoing objectives. More particularly, the present invention involves the discovery that, when the lower alkyl esters, especially the methyl esters of both saturated and unsaturated fatty acids, superior sucker control is achieved without at the same time introducing undesirable residues, inducing undesirable metaboliochanges, or otherwise producing results which are considered in the industry to lower the quality of the tobacco. It was further discovered that certain synthetic growth regulators, notably, isopropyl-N-(3-chlorophenyl) carbamate, which ordinarily cause leaf deformation when applied in amounts effective to control suckers, can now 'be used in amounts as low as one-tenth of those formerly required, when mixed With the fatty acid alkyl esters. Effective control is thus achieved without leaf deformation. In addition mixtures of esters can be used.

Thus, the present invention comprises a method of controlling the growth of suckers in tobacco plants by applying to the tops of decapitated plants, or to plants having newly formed flower buds, a lower alkyl ester of a fatty acid, mixtures of such esters, or a mixture of such an ester with a synthetic growth control substance.

It has been found that the lower alkyl (particularly the methyl) esters of C to C saturated and unsaturated fatty acids are useful for the purposes of this invention, the methyl esters of the C to C fatty acids being particularly effective in concentrations as low as 5%.

In practicing the invention it is merely necessary to prepare an aqueous emulsion of the desired ester and spray it on the decapitated plant or onto the newly formed flower 'buds. Any suitable emulsifying agent can be used in preparing the composition.

Without being bound by the explanation of the mechanism of the action of the esters, it appears that the meristematic and differentiating cells of axillary buds are destroyed when contacted by the fatty acid esters, but cells in advanced stage of maturity are not affected. Thus, the esters do not impair the mature tobacco leaves while they destroy the axillary buds. In addition, because the axillary buds are destroyed on contact, the esters themselves do not take part in the metabolism of the plant and do not enter the tissues of the plant so that the treatment does not cause any changes other than those normally occurring during hand suckering.

Furthermore, many fatty acids, including myristic, pentadecanoic, pentadecenoic, palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic, are naturally present in tobacco leaves, while palmitic, stearic, oleic, and linoleic acids are among the acids naturally present in tobacco seeds. Thus, the application of fatty acid esters according to this invention will not introduce compounds foreign to the composition of the tobacco.

In order that the invention may be better understood, reference is made to the following examples. It will be recognized, however, that these examples are illustrative only and that those skilled in the art will be able to prepare other compositions on the basis of the disclosure without departing from the spirit of the invention.

Example 1 Methyl caprate (95% active) 2 ml. was mixed with .8 ml. of Tween-20 and 40 ml. of water, emulsified and the entire composition sprayed onto the top of the decapitated plant. The area covered by spraying was about 8 inches in diameter. This solution will normally drain down along the stern of the plant and destroy the meristematic and differentiating tissues through contact. This process was repeated after one week. This application gave 96% sucker inhibition in four types of tobacco grown in Beltsville, Maryland, in 1963.

Example 2 A mixture of methyl laurate with methyl myristate was prepared in five formulations containing 50%, 70%, and 96% laurate and 48%, 28%, 18% 8%, and 2% myristate, respectively. 2 ml. of the mixtures of methyl esters plus .8 ml. of Tween-20, and 40 ml. of water. were emulsified and sprayed onto the topped tobacco plant. This gave sucker inhibition of 100%, 99%, 100%, and 99%, respectively.

Example 3 Use 2 ml. of methyl ester mixture of 55% caprylate and 40% caprate and .8 ml. of Tween-20 and 40 ml. of water, emulsified and sprayed onto the topped tobacco plants, gave 100% sucker inhibition.

Example 4 An emulsion of 2 ml. of methyl ester of pelargonic acid plus .8 ml. of Tween-20, and 40 ml. of Water sprayed onto the top of the topped tobacco plant gave 98% sucker inhibition.

Example 5 2 ml. of a mixture of 48% methyl laurate, 17% myristate, 8% caprylate, 7% caprate, 9% palmitate, and

Example 6 Emulsions were prepared as described above, using 1 and 2 ml. portions of methyl caprate (95%), i.e., emulsions containing about 2.5 to 5.0% (v./v.) of ester, respectively, and and mg. of CIPC, isopropyl-N- (3-chlorophenyl) carba mate. When sprayed on decapitated tobacco plants, 96 to 100% sucker inhibition was achieved. The amounts of CIPC were one-tenth and onefifth, respectively, the amounts of that agent normally required to obtain effective inhibition.

it was possible to prevent blossoming and to eliminate the suckering process.

Example 8 A mixture was prepared of 1 ml. of undecenoic acid (C H O 0.8 ml. of Tween-20, and 40 ml. of water. The mixture, after being emulsified was sprayed onto topped tobacco plants, and was effective in preventing the growth of suckers.

In Table 1, below, are listed the data on sixteen experiments using the methyl esters of various commercially obtained fatty acids. The percentages set forth in each horizontal line represent the amounts of the component acids in each commercial acid. Thus, for example, in Treatment No. l, the caprylic acid used consisted of 90% caprylic acid itself, 7% caprioc acid (C and 3% capric acid (C Columns 11-14 set forth the four types of tobacco plant which were treated, while the last column states the average inhibition obtained with each variety.

TABLE 1.PERCENT OF SUCKER INHIBITION OF FOUR TYPES OF TOBACCO [Average of Two Crops, Plants Each Crop] Percent of various fatty acid methyl esters in mixture 1 Percent Sucker Inhibition (3 wks. after topping Treatmerit No. Myris- Palmi- Oleate Lino- Mary- Conn.

Caproate Cap- Caprate Laurate tatc tate Stearate C18 leate land Hicks Burley Broad- Avers rylate C10 C12 C14 Cm Om (-2H) C18 Catter- 21 leaf age Cs (-4H) ton 1 2 ml. of ester mixture emulsified in 40 ml. of Water applied per plant.

2 Applied twice with one week intervals. 3 Glyeerides 25%.

Example 7 From 50 to 100 parts per million of CIP were added to 40 ml. portions of a 5% methyl caprate emulsion (i.e., 40 ml. of emulsion containing about 2 ml. of methyl Table 2 below sets forth data on four treatments involving mixtures of methyl caprylate and CIPC, as well as one using free lO-undecenoic acid and one using methyl pelargonate.

TABLE 2.-TESTS WITH MATERIALS DERIVED FROM OR MIXED WITI-I FATTY ACIDS Percent Sucker Inihibition (3 wks. alter topping) Treatment N0. Composition Maryland Connect- Catterton Hicks Burley 21 icut Average Broadleal 17 Methyl caprylate l 1111. plus 20 mg. OIPCK 98 18- Methyl caprylate 1 ml. plus 40 mg. CIPC. 100 96 19 Methyl caprylate 2 1111. plus 20 mg. OIPCL 20 Methyl eaprylate 2 ml. plus 40 mg. CIPC. 100 94 98 21. IO-undecenoic acid 3 01 112002 100 100 100 22 Methyl pelargonate CHnCHmCOO CH3 93 98 97 1 1 ml. of ester emulsified in 40 ml. of water. 2 2 ml. of ester emulsified in 40 ml. of water. 3 2 ml. emulsified in 40 ml. of water.

caprate and about from 2 to 4 mg. of CIPC) prepared as previously described. These were sprayed onto tobacco plants having newly formed flower buds. Both the flower buds and axillary buds were destroyed. By this procedure Table 3 sets forth data on experiments carried out on field-grown Maryland tobacco for the purpose of comparing the results obtained according to the present in- 5 vention with those using maleic hydrazide, an inhibitor currently in widespread use for inhibiting growth of suckers.

In addition to the percent of sucker inhibition, field appearance was rated based on general plant appearance, leaf appearance, leaf damage, or other abnormalities. Field appearance is rated from 1 to 5, 5 being the highest rating. The product of percent of sucker inhibition and field appearance is called Desirability index. Results from Table 3 shows that maleic hydrazide is ranked 5 in a test of 8 materials.

TABLE 3.DESIRABILITY EVALUATION OF SOME FATTY ACID TREATMENTS IN COMPARISON WITH MALEIC (FIELD-GROWN MARYLAND TOBACCO).

1 The composition of each treatment number is described in Table 1. 2 Average of four replications. Commercially used growth control agent (for purposes of comparison) I claim:

1. A method of inhibiting the growth of suckers on tobacco plants which comprises applying to tobacco plants having newly formed flower buds an amounts of an aqueous emulsion containing isopropyl-N-(3-chlorophenyl) carbamate and a lower alkyl ester of a C to C fatty acid such that there are applied to each plant about 2 ml. of active acid and about from 2 to 4 mg. of said carbamate.

2. The method of claim 1 wherein the ester is methyl caprate.

3. A composition for inhibiting the growth of suckers in tobacco plants comprising a mixture of isopropyl-N- (3-chlorophenyl) car barnate and a lower alkyl ester of a C to C fatty acid in a proportion of about from 20 to 40 mg. of said carbamate to about from 1 to 2 ml. of active ester. 7

4. The composition of claim 3 wherein the caster is methyl caprylate.

5. The composition of claim 3 wherein the ester is methyl caprate.

6. A method of inhibiting the growth of suckers on tobacco plants which comprises applying to topped tobacco plants an amount of an aqueous emulsion containing a lower alkyl ester of a C to C fatty acid and isopropyl-N-(3-chlorophenyl)carbamate such that there are applied to each plant from 1 to 2 ml. of active ester and from 20 to 40 mg. of said carbamate.

7. The method of claim 6 wherein the ester is methyl caprylate.

8. A composition for inhibiting the growth of suckers on tobacco plants comprising an aqueous emulsion containing about from 2.5% to 5.0% (v./v.) of a lower alkyl ester of a C to C fatty acid and an amount of isopropyl- N- (3-chlo-rophenyl)carbamate such that 40 ml. of said emulsion contains about from 20 to 40 mg. of said carbamate.

9. The composition of claim 8 wherein the ester is methyl caprylate.

10. The composition of claim 8 wherein the ester is methyl caprate.

References Cited UNITED STATES PATENTS 2,585,875 2/1952 Swaney et al. 71-26 2,622,976 12/1952 Hitchcock et al. 712.7 2,772,152 11/1956 Emond et a1. 712.7 X 2,789,044 4/1957 Steinmetz 712.7 2,876,089 3/1959 Brugman et al 71-2.6 3,223,517 12/1965 Abramitis et al. 712.7 3,253,904 5/1966 Harrison 712.6

OTHER REFERENCES Tso et a1.: Chemical Abstracts, vol. 59, 1963, col. 8064(e).

LEWIS GO'ITS, Primary Examiner.

JAMES O. THOMAS, Examiner.

A. J. ADAMCIK, Assistant Examiner. 

1. A METHOD OF INHIBITING THE GROWTH OF SUCKERS ON TOBACCO PLANTS WHICH COMPRISES APPLYING TO TOBACCO PLANTS HAVING NEWLY FORMED FLOWER BUDS AN AMOUNTS OF AN AQUEOUS EMULSION CONTAINING ISOPROPYL-N-(3-CHLOROPHENYL) CARBAMATE AND A LOWER ALKYL ESTER OF A C6 TO C18 FATTY ACID SUCH THAT THERE ARE APPLIED TO EACH PLANT ABOUT 2 ML. OF ACTIVE ACID AND ABOUT FROM 2 TO 4 MG. OF SAID CARBAMATE. 